边石的材料

例句：

1. 1. The riverbank is covered in smooth stones.
   河岸覆盖着光滑的石头。
2. 2. The stone carvings on the wall are fascinating.
   墙上的石雕令人着迷。
3. 3. The stone archway leads to the main street.
   石拱门通往主街。